In many everyday situations individuals’ choices are a result of a routine behaviour in a familiar situation. The choices are made almost without elaboration and the preceding choice process is far from the traditional five step decision process (Dewey, 1910; Simon 1955, 1956) that is assumed to occur in a more deliberate problem solving situation (Svensson, 1992). In many situations it is of interest to change habitual behaviour. Society, for example, might be interested in changing a routine behaviour to promote pro-environmental behaviour. Such behaviour can for instance, be to abandon the routine choice of automobile as a travel mode for daily trips. Changing a routine behaviour requires an understanding of how a routine behaviour is formed and what factors can be used to predict such behaviour. This paper focuses on measures of routine behaviour and corresponding actual behaviour. More specifically, this paper investigates if differences in car use in the household can be explained by differences in spouse’s attitude to cars and/or their car use behaviour. Traditional research of decision making is based on a deliberate choice process and as a consequence, theories are based on extended problem solving. For example, theory of planned behaviour (Ajzen, 1985) have been developed and used as a platform in research dealing with prediction of future behaviour (i.e. attitude – behaviour relation). Attitudes have however shown weak correlations with daily and repetitive behaviour and recent research on habitual behaviour indicate that measures of past behaviour predict future behaviour over and above measures of attitudes and intentions (Bentler and Speckart, 1979; Verplanken et al, 1997). Another measure used to predict future routine behaviour is ‘response frequency measures’ (Verplanken, et al 1997). By presenting a variety of travel items to an individual it is assumed that his/her travel ‘script’ is activated and the more often a specific travel mode is indicated the stronger the habit to use that particular mode. ‘The response frequency measure’ have been used and validated in a number of studies, for example, to measure car choice habit among commuters. In summary, three different measures have been used to predict behaviour; attitudes, past behaviour, and scripts, where the two latter have proven to be more useful in predicting habitual behaviour. In many households the number of adults often exceeds the number of cars and the household members have to divide the usage of the automobile between them. Many studies indicate that men use the car for commuting to work whereas females use the automobile for shopping and service activities (Krantz, 1999). In a situation where the individual is constrained by the spouse’s behaviour, different behaviour patterns are likely to emerge. By comparing the attitudes towards travel modes, scripts, and past behaviour between the dyad members and relate these measures to actual behaviour an increased understanding of both measures of habitual behaviour and actual routine behaviour might be generated. Additional information of habitual behaviour can be identified if the different measures also are related to different types of activities. It might, for example, be possible that the household members have the same attitude towards a travel mode (car), but that their behaviour/usage differs. In this study dyads attitudes and travel behaviour has been investigated in households with two adults and one car. Both spouses kept a detailed travel diary during one week. In addition, measures of attitudes towards different travel modes, past behaviour, and response frequency measures, ‘scripts’ were collected. The results show that spouses in general have similar attitudes towards cars and other travel modes such as bus, bikes and pedestrian walking. Spouses also show similar attitudes towards car usage. However the results show different car usage pattern among the studied spouses. Men, for example, drive more often than women; men also, more often than women, have an established car habit. Moreover, spouses with the same attitude engage in different car usage, such that men use the car for work related trips whereas women us the car for shopping trips. The results support earlier findings in that attitudes are not a good predictor of habitual car usage. However, attitudes are neither a good predictor of more thought through car usage. Also for less habitual behaviour past usage or response frequency measures are better predictors. Analyses using the response frequency measures show that men have a stronger link between the activated travel goal and the choice of car as travel mode, than women have, even tough a relation was found between spouse’s respective car habit strength. In the given situation where each individual is constrained by the spouse’s habits and behaviour, different behaviour patterns were found. The behavioural effect of the male car habit was conditioned to the women not having a strong car habit. The results thus support the view of a competitive situation between spouses for the only available car.